Safety valve for hydraulic brakes



061.28, 1947. KEAN v 2,429,820,

SAFETY VALVE FOR HYDRAULIC BRAKES ,0t.2s ,1947. J GQW'KEAN' 2,429,820

SAFETI-YALVE-FOR HYDRAULIC BRAKES Filed March 22, ,1945 2 Shgets-Sheet 2 IN V EN TOR. v Gea/ye 1 k Razz AFOIPJVEY Patented Oct. 28, 1947 UNITED STATES PATENT OFFICE SAFE TY VALVE FOR HYDRAULIC BRAKES George W. Kean, Granby, Conn. I

Application March 22, 1945, Serial No. 584,184 (01. 303-414) 4 Claims.

The invention to which the following specification relates is in safety cut-oils for hydraulic brake systems.

The application of hydraulic brakes to the separate wheels of a motor vehicle by foot applied fluid pressure transmitted from a. single source such as a master cylinder is subject to dilficulties which most frequently arise at the times when the operator is placing greatest reliance on the mechanism. Thus a-sudden rupture of one of the several operating connections or conduits from the master cylinder to the brake applying cylinders will cause the sudden loss of the operating liquid in large quantity as well as causing a complete failure in the application of the brake to which the conduit or tubing is connected.

It is also well known that the gradual leakage of pressure fluid from a brake system results finally in the development of a situation where there is not enough pressure applied to the individual brakes to be efiective. There is thus a loss of pressure in the brake at one wheel which may impair the effectiveness of th brake pressure applied to the remaining wheels. same time this condition gives rise to slow depletion of the fluid supplied in the master cylinder and the system thus becomes inoperative,

Wear in either the power applying cylinders at the wheels, or in the brake drums or brake shoes will also render the system inoperative as it will demand an excess quantity of the pressure fluid without obtaining adequate braking effect.

A primary object of my invention is to provide a positive cut-off for the pressure fluid in any one of the operating conduits or tubing of a brake system to which it may be connected.

This cut-01f is designed to operate promptly on the occurrence of any abnormal condition during the application of the fluid pressure to apply the brake. Thus the sudden rupture of a single brake operating conduit will result in the cut-off ofthe fluid supply to an individual or a pair of brakes without, however, impairing its application to the remaining brakes.

Another object of my invention is to cut off the supply of pressure fluid where it is being delivered withoutefiect on the brakes due to slow leakage. In other Words the discharge of an excess quantity of pressure fluid without development of brake operating pressure results in actuating the cut-off. I

A further object of my invention is to actuate the cut-off When the compressible bellows used to transmit pressure from the master cylinder to A he.

a pair of brakes or to an individual brake becomes Worn, unresponsive or collapses.

Other objects of the invention will be apparent from the following description of the preferred form of the invention as illustrated in the accompanying drawingin which:

Fig. 1 is a longitudinal cross section taken on the line l--l of Fig. 3,, of my improved device in normal or operating position;

Fig. '2 is a similar longitudinal section of the same mechanism as in Fig. 1 showing the cut-off operated by leakage of pressure in one of the brake tubings due to rupture or slow leakage;

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 1 showing the cut-off plug in normal position;

Fig. 4 is an isometric view of the cut-off valve; and

Fig. 5 is an outside view of the cut- 01i valve shown in Figs. 1 and 2 associated with a storage tank for fluid used in the brake system. I

Thissafety device consists generally of a chamber receiving fluid pressure from a master cylinder or the like, means for applying this pressure to develop operating pressure in the brake cylinders and an associated cut-01f valve in the pressure applying conduit. One of these units Will be mounted in the conduits from the master brake cylinder to the individual or pairs of brake cylinders at the wheels. The pressure developed by the braking fluid in the system operates to actuate the cut-oil valve on the occurrence of failure of pressure in the braking piping. Thus a chamber 4 receives the pressure directly from the master cylinder or the likethrough a pipe connection at the end fitting 5. The end of the chamber 4 opposite the fitting 5 is formed by a ring 6.

Within the chamber 4 there is a compressible bellows 7. One end of this bellows is anchored to the ring 6 while the opposite end is in the form of a disk 8 closely adjacent to the end of the chamber which has the fitting '5. This bellows has normal resilience but may be compressed to the degree indicated in Fig. 2, by the use of pressure in chamber 4 exceeding that in the pressure applying or brake operating tubing.

Disk 8 is fitted with a longitudinal shaft or rod 9 which projects beyond the end ring 6 of the pressure chamber and is reciprocated longitudinally whenever fluid pressure is applied through the fitting 5 to the interior of the chamber 4, and against the sides and end of the bellows A cylinder I0 is provided and adapted for fitting on the open end of the pressure chamber 4 and opposite the ring 6. An end plate H is fitted over 3 the end of the cylinder l and forms a stop for plunger presently to be described. The ring 6, the plate H and the flange of the cylinder ID are clamped together in liquid tight relation.

The opposite end of the cylinder [0 is closed by means of an end plug l2 which is suitably fitted over and suitably secured to the end of the cylinder. The end plug [2 has a screw-threaded fitting 13 which in turn is connected by means of a longitudinal bore 14 to the interior of the cylinder ID.

A transverse bore 15 passes through the end plug 12 and also has registering openings I6 and I! in the cylindrical side wall of the cylinder I0. These openings l6 and l'l'are suitably closed by means of pipe plugs l8 and I9. The transverse bore 15 intersects the longitudinal bore [4.

A cut-off plug or valve 2!] slides vertically in the transverse bore [5. This plug has an annular groove 2| which registers with the bore I4 when the plug is in its upper or normal position. A coil spring 22 between the upper end of the plug 20 and the pipe plug 19 urges the plug 29 into its closing position whenever the plug is released.

There is a longitudinal opening 23 in the end plug l2. This opening is parallel to the bore E4. The opening is relatively large at the outer portion of the end plug where it receives a pipe plug 24. There is also on the head 12 an intermediate diameter opening 25 where the opening or bore 23 intersects the transverse bore l5. Inwardly of the bore l5, there is a small opening 26 aligned with bore 25 and extending into the interior of the cylinder II].

A latch pin 21 is provided for movement in the openings 25 and 21. The pin has a minimum diameter where it passes through the openin 26 and a larger diameter 28 in the opening 25. A flanged head 29 is provided on the outer end of the latch pin and is received in the opening 23 where it is held in the inward position by means of coil spring 29. In this inward position the intermediate diameter or shank 28 projects into the bore l5.

The upper end of the plug 29 is provided with a narrow slot 30 as shown in Fig. 3. This terminates at its lower end in a large circular opening 3| which runs transversely of the plug 20 and when the plug or valve 20 is in its open position this opening 3| registers with the opening 25 in the cylinder head.

The shank 28 of the latch pin projects into the opening 3| and serves to hold the plug 20 in its upper or open position against the force of the spring 22. However, when the projecting end 21 of the latch pin is driven outwardly the shank 29 moves beyond the bore l and the cut-off plug is released to drop into closing position across the opening M. This movement is accelerated and assured by the coil spring 22.

It will be apparent that the cut-off plug can be restored to open position by removal of the pipe plug I8 when the cut-off plug may then be manually lifted into open position where the latch pin 28 will engage the circular opening 3!.

The cylinder ID has a slidable sleeve 32 which is held against the stop II by means of the coil spring 33. This sleeve has a transverse partition or seat across one end and a relatively large central bore through which the rod 9 projects. A pressure relief valve 35 passes through this seat and serves to transfer liquid to the left as shown in Fig. 1 to equalize pressures whenever pressure in the master cylinder is released.

Between the seat 34 and the cylinder head I2,

the rod 9 carries a piston 36. This piston is loosely fitted on the rod 9 and has a conical end conforming to the seat 34 against which it is held by the spring 31. A supplemental spring 33 extends between the cylinder head and the flanged end of the piston 34 so that the return of the piston 36 to its normal seating position is accelerated. Piston 36 is free on rod 9 so that in case of bellows failure piston 34 and piston 36 can move to right as a unit, spring 31 being stronger than spring 33 to insure engagement of piston 36 on its seat.

In normal position pressure applied by means of the master cylinder to the pressure chamber 4 serves to compress the bellows 1 moderately. This results in lifting the piston 36 from the seat 34 and fluid pressure from within the bellows is then applied around the flange of the piston 33 and directly through the open bore I4 to the brake operating mechanism.

In normal operation the braking effect is accomplished before the bellows i is fully collapsed or and before the piston 36 approaches the cylinder head close enough to engage the latch pin 27. Therefore the cut-off plug remains in its upper or open position throughout the pressure applying step. On release of the pressure in the master cylinder the bellows 1 is restored to its expanded position and the spring 31 brings the piston 36 into seating engagement again. During this operation the pressure relief valve 35 will complete the transfer of enough liquid from the cylinder Ill into the bellows l to equalize pressure.

If however, there is a break in the tubing to the working cylinder of an individual brake or leakage is excessive there will benothing to retard the movement of piston 36 and it will overcome the force of spring 31. Piston 36 then comes in contact with the latch pin 21 and drives the portion 28 of the latter out of engagement with the cut-off plug. The latter, under the influence of spring 22 drops down into closed position blocking further escape of pressure fluid. This conduit therefore remains out 01f regardless of change in the position of the piston 36 or its retraction to normal inoperative position.

In the event that the bellows 1 becomes ineffective or so worn as to collapse under the pressure of the pressure fluid, then leakage Or pressure fluid through the bellows or the sudden application of equivalent pressure within the bellows will overcome the forces of springs 33 and 37 and cause the sleeve 32 to slide toward the 03 1- inder head carrying with it piston 36. As a result piston 36 will then release the cut-off plug 29 in the manner above described.

It will be apparent from the above that I have provided a simple and effective means for preventing undue loss of pressure fluid in braking systems where they have been rendered inoperative or defective by breaks or leakage in the conduits leading to the brake cylinders.

The brake operating movement itself serves to actuate a positive cut-oil which is then permanent until the cut-01f plug is manually reset. The operation also is carried out without disturbing the normal functioning of the remaining operative par-ts of other individual brakes.

The operation of the cut-off occurs in the event of any abnormal condition in the braking mechanism whether it is a matter of excess wear on the parts, slow leak or accidental rupture of the tubing.

Again if the bellows becomes broken or inoperative the pressure applied directly on the slide member 34 serves to cause the indirect actuation of the cut-off valve.

To permit, the bellows 1 to return to its normal or expanded position after the cut-01f valve 29 has operated, a storage tank 40 may be associated with the valve structure I0. Conduit I 3 is connected to this tank 40 and a supplemental conduit 4| leading from the tank 40 extends to the brake or brakesto be operated.

Also leading from the tank 40 is a return conduit 42 extending to an intermediate portion of the body portion [0 so that fluid may pass from the tank 40 t0 the valve chamber and permit return movement of the bellows 1. In this conduit 42 is a check valve 43 preventing fluid from passing from conduit 42 into the tank 40.

While the preferred form is illustrated and described, minor changes in detail and proportions will suggest themselves as within the scope of the invention as defined in the following claims.

What I claim is:

1. A cut-ofl for brake-operating fluid pressure conduits comprising a, chamber having an inlet for pressure fluid, a bellows closing one end of the chamber, a cylinder connected to the end of the chamber, a cylinder head having an outlet passageway, a cut-01f valve'for the passageway, a latch projecting into the cylinder and holding the cut-off valve in open position, a piston in the cylinder and means connecting the bellows with the piston for releasing the latch and permitting movement of said valve to its closed position when said piston moves to an extreme position.

2. A cut-off for brake-operating fluid pressure conduits comprising a chamber having an inlet for pressure fluid, a bellows closing one end of the chamber, a cylinder connected to the opposite end of the chamber, a cylinder head having an outlet passageway, an intersecting transverse bore in said cylinder head, a cut-off valve in said bore, resilient means to move the valve into position closing said passageway, a latch pin holding the plug in retracted position, a. piston in the cylinder, a rod connecting the bellows with the piston, said pin projecting into the path of the piston for releasing the cut-off valve when said piston has moved to an extreme position.

3. A cut-off for brake-operating fluid pressure conduits comprising a chamber having an inlet for pressure fluid, a bellows closing one end of the chamber, a cylinder connected to the end of the chamber, a cylinder head having an outlet passageway, a transverse bore intersecting the passageway, a cut-01f valve slidable in the bore, an opening from'the transverse bore into the cylinder, a latch pin journalled in said opening, normally holding the pin in engagement with the valve and means in the cylinder responsive to fluid pressure for disengaging the pin from the valve to permit movement of said valve to its closed position.

4. A cut-oif for brake-operating fluid pressure conduits comprising a chamber having an inlet for pressure fluid; a bellows closing one end of the chamber, a cylinder connected to the end of the chamber, a cylinder head having an outlet passageway, a transverse bore. intersecting the passageway, a cut-off valve slidable in the bore, said valve having a slotted end and a connecting transverse opening, an opening from the transverse bore into the cylinder, a latch pin journalled in said opening and projecting into the cylinder, an enlarged head on the in for slidable engagement in said transverse opening of the valve, resilient means for holding the pin in its projecting position and means in the cylinder responsive to the fluid pressure admitted to the chamber for disengaging the pin from the valve and permitting movement of said valve to its closed position.

GEORGE W. KEAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,952,557 Masteller Mar. 27, 1934 2,111,930 Hinckley Mar. 22, 1938 2,128,853 Roen Aug. 30, 1938 2,130,799 Hofstetter Sept. 20, 1938 FOREIGN PATENTS Number Country Date 547,062 France Sept. 11, 1922 

